-LRB- CNN -RRB- -- Hours after a security breach forced the closure of a terminal at the Newark , New Jersey , airport Sunday , authorities were still searching for a man who went the wrong way through a checkpoint exit .

The incident happened at about 5:20 p.m. at Terminal C , when an individual walked from the public side to the secure `` sterile '' side for passengers who had cleared screening , according to the Transportation Security Administration .

No flights were allowed to leave from Terminal C Sunday evening and thousands of other travelers who had reached the sterile area after going through checkpoints were moved back to the public area to be re-screened , the TSA said .

Authorities are reviewing video from airport cameras . They are not sure whether the man was once on the sterile side and went back , or if he never went through screening , TSA spokeswoman Anne Davis said .

Watch more about the situation in Newark

The incident caused arrival delays and mainly affected Continental Airlines , which is the airport 's largest tenant .

CNN 's Alina Cho , who arrived at the airport Saturday night on a flight from Fort Lauderdale , Florida , described the hectic scene : `` For the people who are hoping to fly out of Newark this evening , there is not a lot of movement . ''

She said many passengers who had already boarded outgoing flights had to get off planes to be re-screened .

`` I just saw one woman pleading with a gate agent , saying that she had two small children and a heart condition -- that she simply could not take this , '' Cho said . `` But of course , there will be no exceptions . ''

Flying Continental ? Important company notice

Newark Liberty International Airport , which is about 15 miles from Manhattan , is the second-largest hub for Continental .

The airport handles about 35 million passengers a year .

CNN 's Susan Candiotti and Ross Levitt contributed to this report .

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TSA : Man walks through wrong side of checkpoint exit

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Police seek the individual , who walked from the public side to the sterile side

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No flights allowed to leave from Terminal C Sunday evening

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Incident causes arrival delays and mainly affected Continental Airlines